Read the paper for this work, published in PLoS ONE:
A Glucose Fuel Cell for Implantable Brain–Machine Interfaces
Rapoport BI, Kedzierski JT, Sarpeshkar R (2012) A Glucose Fuel Cell for Implantable Brain–Machine Interfaces. PLoS ONE 7(6): e38436. doi:10.1371/journal.pone.0038436
Conceptual schematic design for a system that harvests power from the cerebrospinal fluid, showing a plausible site of implantation within the subarachnoid space. The inset at right is a micrograph of one prototype, showing the metal layers of the anode (central electrode) and cathode contact (outer ring) patterned on a silicon wafer. Image Credit: Meninges and Vascular Anatomy courtesy of the Central Nervous System Visual Perspectives Project, Karolinska Institutet and Stanford University.